Method and apparatus for incorporating coloring matter in spinning solutions



June 3, 1958 R. F. BAUER ET AL 2,837,102

METHOD AND APPARATUS FOR INCORPORATING COLORING MATTER IN SPINNING SOLUTIONS Filed Dec. 20, 1954 s mums' SOLUTWN 9N lb liv z x" K J & meMsN'r composrnou A I5 INVENTORS A RALPH F- BAUER ATTO RN METHOD AND APPARATUS FOR INCORPORAT ING COLORING MATTER IN SPINNING SOLU- TIONS Ralph F. Bauer, Chagrin Falls, and Kenneth M. McLellan,

Cleveland, Ohio, assignors to Industrial Rayon Corporation, Cleveland, Ohio, a corporation of Delaware Application December 20, 1954, Serial No. 476,536

8 Claims. (Cl. 137--7) This invention relates to a method and an apparatus for incorporating metered amounts of coloring matter may be prepared with improved fastness to light and to laundering and can be provided with other desirable characteristics, such as more uniform coloration and shade intensity by incorporating the coloring matter in the spinning solution prior to extrusion. Yarns so produced from viscose and other fiber-forming materials are known as being spun-dyed, dope-dyed or solution-dyed yarns.

In the production of spun-dyed colored yarn and the like from viscose it has been found advantageous to continuously admix and blend coloring matter into'the ripened viscose prior to extrusion and after the ripened viscose, in a suitable condition for spinning, has been delivered from storage or spin tanks to a spinning machine. Analogous techniques, wherein a spinning solution ready for extrusion is colored while being transmitted to a spinning machine may also be beneficially employed in the production of colored yarn products and the like from other fiber-forming materials. When practicing the aforementioned technique, the necessity and inconvenience of color blending spinning solutions in batches prior to delivery to the spinning machine for extrusion can be eliminated and worthwhile economies may be realized in maintenance and cleaning of equipment. Also, possible losses due to miscolored spinning solution can be minimized Whenever it may be desired to alter or change the color of the yarn being spun. The avoidance of losses of miscolored spinning solution is especially pertinent in the case of viscose spinning solu tions which cannot conveniently be stored over prolonged periods for subsequent use once they have aged or ripened to a suitable condition for spinning.

In order that consistently similar colored yarn prod ucts may be produced from day to day when a spinning solution is being continuously blended with coloring mate te'r, it is important that constant unit proportions of any particular coloring matter be continuously and consistently introduced and blended into unit volumes of the spinning solution during unit periods of extrusion. This is especially so when the spinning solution being colored is being supplied for continuous extrusion through a plurality of spinning positions, and position-to-position as well as day-to-day variations in the colored yarn United States vtent product are to be avoided. Among the various coloring.

matter which may be employed for coloring spinning solutions, pigments are known .to be desirable. They areespecially suitable for viscose spinning solutions. It is advantageous to employ coloring pigments in the form 2,3311%?! Patented .lune 3, 1958 ICE of liquid pigment dispersions in order to circumvent the difliculty with which dry pigments of generally fine particle size are blended directly into a viscose spinning solution and to avoid an irregulardistribution of the coloring matter throughout the spinning solution. Liquid dispersions enable a more intimate, uniform mixing of the coloring matter with the spinning solution to be attained in order to obtain suitable homogeneity in the colored mass. The liquid in which the pigment is dispersed should, of course, be compatible with the particular spinning solution to be colored.

Generally, liquid pigment dispersions, such as aqueous pigment dispersions, sometimes referred to as pigment pastes, are thin, watery fluids of relatively low viscosity which may have various contents of solids. However, when attempts are made with conventional metering devices, as gear pumps, to continuously anddirectly inject a liquid pigment dispersion, such as'a pigment paste, for blending into a spinning solution whichis flowing under pressure, difliculties are encountered in admixing constant proportions of the liquid pigment composition into the spinning solution.

Among the more desirable metering devices that are generally employed for delivering constant volumes of' liquids over unit periods of time are gear pumps. Gear pumps, for example, are commonly preferred for the extrusion of viscose and of other relativelyviscous spinning solutions and compositions for spinning since they are especially adapted to deliver relatively thick or viscous liquids at substantially constant rates. However, because of slight clearances between the rotors and the casing in gear pumps, they are not Well adapted for metering relatively low viscosity'or thin fluids against viscose, flowing under pressure.- a

The dithculties are especially aggravated when there is an appreciable fluctuating, or even static, variation between the feed pressure of the liquid pigment composition at the pump inlet and the delivery pressure at the pump outlet; Such variations in the pressure differential across the pump often occur over a wide range. For example, when pigment paste is injected into a viscose feed line, variations of as much as 40 pounds per square inch (p. s. i.), or greater, may be encountered due to the manner in which viscose and other spinning solutions are conventionally handled. Obviously, the injection pressure of the liquid pigment composition must meet or exceed the pressure under which the spinning solution is flowing. When gear pumps are used for this purpose, difliculty in keeping a desired volumetric ratio of the liquid pigment composition withintolerable consistent limits in a spinning solution may be experienced due to the heretofore mentioned deficiencies of gear pumps in such situations. For example, variations of more than about 5% in the pigment content of viscose are known to be visually discernable in colored yarn products produced therefrom. As a consequence, variations, greater than about this amount of the pigment content of viscose and other types of spinning solutions result in objectionablespinning position-to-position and day-to-daydifierences in the colored yarn product.

The preseht invention advantageously provides for a method and an apparatus in which a constant delivery device, such as a gear pump, may be employed for precisely and continuously introducing and incorporating liquid pigment compositions, as pigment paste, into spinning solutions of ripened viscose or other compositions which are flowing under varying pressure to produce consistently evenly colored yarns and the like. The apparatus is capable of handling liquid pigment compositions to inject them in spinning solutions under pressure in amounts Within tolerable consistent limits so that objectionable spinning position-to-position and day-to-day shade differences in the colored yarn product may be avoided.

In accordance with the present invention, a metering gear pump may advantageously be directly employed for precisely incorporating measured amounts of a liquid pigment composition in spinning solutions flowing in a conduit under pressure by overfeeding the liquid pigment composition from a supply source to the point at the metering pump predetermining the amount to be injected and circulating the surplus liquid pigment composition overfed to the point of injection at the gear pump througha constrictable passageway which is actuated by spinning solution from the conduit to restrict the flow and increase the pressure of the liquid pigment composition proportional to the pressure of the spinning solution so that the pressure of the liquid pigment composition at the inlet of the metering pump is substantially equalized to that of the spinning solution in the conduit.

Apparatus in accordance with the present invention is comprised of a circulating pump for overfeeding the liquid pigment composition from a supply reservoir to a series connected metering gear pump which injects desired measured quantities of the pigment composition into the spinning solution in the conduit. A return line from the circulating pump outlet to the supply reservoir circulates the surplus pigment composition which has been fed to the metering pump by the circulating pump in excess of its capacity. Advantageously, the surplus pigment composition is circulated to be returned to the supply reservoir. There is provided in the return line a control valve that is directly responsive to varying pressures of the spinning solution in the conduit. Advantageously, the control valve in the return line has a flexible diaphragm providing a constrictable passageway for the surplus pigment composition which has been overfed to the. metering pump by the circulating pump. The flexible diaphragm is hydraulically actuated by spinning solution from the conduit. An increase in spinning solution pressures causes a constricting movement of the flexible diaphragm in the return line passageway through the valve to restrict the flow of the circulating surplus pigment composition in the return line. This equalizes the pressure at the metering pump inlet to substantially that of the spinning solution in the conduit and effectively maintains these pressures substantially equalized through variations I of the spinning solution pressure.

The equalized and controlled feed pressure of the pigment composition to the metering gear pump prevents substantial pressure diflferentials from occurring across the metering pump whenever the back pressure at the pump outlet fluctuates due to changes in the spinning solution pressure in the conduit. In this way, a pigment composition may be consistently and accurately volumetrically metered by the apparatus into a spinning solution within tolerable limits over unit periods of time.

Other additional object and advantages of the present invention will be' apparent in the following description and the drawing in which;

Figure 1 is a schematic representation of an apparatus for practicing'the method of the present invention; and

Figure 2 schematically illustrates in greater detail an embodiment of the controlvalve, depicted in cross section, which is employed for substantially equalizing'the pressure at the metering pump inlet with that of the flowing spinning solution.

With reference to Figure 1, the liquid pigment composision, such as pigment paste, is stored in a supply reservoir 3 from which it is withdrawn by a circulating pump 6, which may be a gear pump or any other desirable type of constant deliveryv pump, and transmitted through the feed line 4. A shut off cock 5 is positioned in the feed line 4 ahead of the circulating pump 6. The delivery output of the circulating pump 6 is proportioned to overfeed the pigment composition to v a series connected metering gear pump '7 in the feed line 4. Advantagcously, the delivery output of the circulating pump 6 may be from about 3 to about times the volumetric capacity of the metering pump 7. The circulating pump 6 should be capable of developing a sufficient hydrostatic head to exceed the maximum spinning solution flow pressures anticipated.

The metering pump 7 delivers desired predetermined measured quantities of the fluid pigment composition through the injection line 22 and a valve 23 for incorporation in the spinning solution flowing under pressure for subsequent extrusion through the conduit 24. The spinning solution containing the incorporated pigment composition is blended in a suitable blender 25, for example, a disc blender which intimately combines the material between closely spaced rotating discs. After blending, the pigmented spinning solution is further passed through the conduit 24 to a supply manifold or header 26 from which it is delivered through a plurality of conduits 27 to be extruded at a plurality of spinning positions (not shown).

The surplus pigment composition overfed by the circulating pump 6 to the metering pump 7, in excess of its capacity, is by-passed and circulated through a return line 8 to the supply reservoir 3. Positioned in the return line 8 is a control valve, indicated generally by reference numeral 9, that is directly responsive to varying pressures of the spinning solution flowing in the conduit 24 to proportionately vary the rate of flow of the circulating surplus pigment composition in the return line 8. The control valve 9 communicates with the conduit 24 through a branch line 20 and a shut off cock 21 to admit the spinning solution from the conduit 24 against the flexible diaphragm 16 in the control valve. The flexible diaphragm 16 provides a constrictable passageway 10 through the valve 9 in the return line 8 for surplus pigment composition overfed to the metering pump 7 by the circulating pump 6. When the flexible diaphragm 16 is hydraulically actuated by increasing spinning solution pressures in the conduit 24, its constricting movement in the constrictable passageway 10 restricts the rate of flow of the circulating surplus pigment composition in the return line 8 to eflect an increased pressure at the inlet of the metering pump 7 which is substantially equalized with the flow pressure of the spinning solution in the conduit 24. Conversely, a decreasing spinning solution pressure permits the constrictable passageway 10 to open and allow the pigment composition to circulate more freely at an increased rate of flowin the return line 8 under reduced pressure. Thus, the control valve 9 eflectively maintains the pressure at the inlet to the metering pump 7 substantially equalized with varying spinning solution pressures in the conduit 24. As mentioned, this prevents the pressure difierential across the metering pump 7 from fluctuating with varying spinning solution pressures. Ordinarily, according to the present invention, the pressure of the liquid pigment composition at the inlet of the metering pump is substantially equalized to that of the spinning solution to a sufficient degree so that the pressure diflerential across the metering pump seldom reaches or exceeds about two pounds per square inch (2 p. s. i.). This permits consistently accurate metering of the pigment composition into the spinning solution.

The control valve 9, shown in greaterdetail in Figure 2, comprises a body 11 that is internally divided by a rigid separator 17 into a chamber 12 for receiving spin ning solution under pressure (as indicated by the directional arrow) and an inlet port 13 and outlet port 14 for the pigment composition. The inlet and outlet ports 13 and 14 are separated by the body portion or barrier 15, integral with the body 11 of the valve. The barrier 15 is sealed against the separator ,17 by a gasket 18. The flexible diaphragm 16, which advantageously may be of rubber or of a rubber-like material, is flatly disposed against the separator 17 in the spinning solution chamber 12. The constrictable passageway for the pigment composition is provided between the diaphragm 16 and separator 17. A pair of apertures 19 through the separator 17 and gasket 18 communicate between the constrictable passageway 10 and the inlet and outlet ports 13 and 14 to provide access for the pigment composition through the constrictable passageway in a flow path as indicated by the directional arrow. The constrictable passageway 10 is relatively shallow and of substantial area so that under maximum spinning solution pressure the flexible diaphragm 16 is pressed closely against the rigid separator 17. Also, the apertures 19 are advantageously of relatively small dimensions. The physical proportions of the control valve 9 depend to a great extent upon the volume of pigment composition being handled and by-passed, as will be apparent to those skilled in the art.

If desired, a narrow groove or slit (not shown) may be provided in the separator 17 between the apertures 19 against the diaphragm 16 to insure circulation of some of the by-passed. pigment composition through the valve 9 in the return line 8 even under spinning solution pressures which may be sufiicient to cause the diaphragm 16 to be pressed completely flat against the separator. However, in some cases, such construction is not required since suflicient passage of the pigment composition is normally permitted between the diaphragm 16 and separator 17 under maximum spinning solution pressure to permit circulation of suificient surplus pigment composition through the return line for properly regulating the feed pressure at the metering pump inlet. I

In order to further illustrate the invention but without being limited thereto, the following example is given:

EXAMPLE A pigment paste containing about 20% by weight of dry copper phthalocyanine (Monastral Blue) is directly injected with a metering gear pump into a ripened viscose spinning solution flowing in a conduit under varying pressure using apparatus arranged similar to that depicted and described in Figure 1. The circulating pump employed has a volumetric capacity about ten times the capacity of the metering gear pump with which 'it is intended to directly inject about 6 grams of the pigment paste per minute into the flowing viscose to obtain a product having the desired coloration. After injection and prior to extrusion, the incorporated pigment paste is intimately blended with the viscose in a double disc blender. The control valve in the circulating line through which the surplus pigment paste overfed to the metering pump is by-passed has a constrictable passageway formed between a rubber diaphragm of about A2 inch thickness flatly disposed completely over a generally circular separator of about 1% inches diameter having apertures for pigment paste with diameters of about 4; inch. Viscose under pressure from the viscose line conduit is admitted against the diaphragm. The pigment paste being by-passed through the control valve is returned to the supply reservoir from which it is withdrawn by the circulating pump. Variations in viscose line pressure over a range of about 40 p. s. i. result inpressure difierentials across the metering pump which are not greater than about 2 p. s. i., as indicated in the following table of results:

Pigment Pressure Average Flow Viscose Paste Difierof Pigment Line Pressure at ential Paste Pressure Inlet To Across Through (p. s. i.) Metering Metering Metering Pump Pump Pump (p. s. i.) (p. s. 1) (grams/min.)

The volumetric difference in the rate of pigment paste being metered over theentire range of viscose line pressure variation is about 18 parts out of 600 or about 3%. This is a tolerable variation of pigment content in the spun-dyed product. Without employing the control valve to equalize the pressure differential across the metering pump, a substantially greater variation of about 4 parts by volume out of 14 is experienced over about the same range of viscose line pressure fluctuation. This results in more than 28% variation in the pigment content of the viscose which renders easily perceptible differences of an intolerable degreein the coloration of the yarn product.

Liquid pigment compositions having, generally, any particular viscosity characteristics may be handled by the method or with apparatus according to the present invention. However, if unusually thin compositions are being employed, it may be desirable to thicken them to a more suitable viscosity, especially if an exceedingly precise and accurate pigment content is desired in the colored yarn product. Various thickening agents are known and may be employed for this purpose. Their use for a liquid pigment composition need not, in any event, occasion modifications or alterations in the practice of the present method or in the design or operation of the present apparatus.

Since various changes and modifications may readily be made in the practice of the present invention with out substantially departing from its spirit or scope, it is to be fully understood that all the foregoing description be interpreted as merely illustrative and in no sense limiting or restrictive of the invention as particularly pointed out and defined in the appended claims.

What is claimed is:

1. Method for directly incorporating a metering gear pump fed liquid pigment composition into a spinning solution under pressure for subsequent extrusion into colored yarn and like products comprising; overfeeding the liquid pigment composition to a point in a conduit predetermining the amount to be injected into a flowing spinning solution under pressure; injecting a predetermined amount of said liquid pigment composition into said spinning solution at said point; and by-passing the overfed liquid pigment composition through a constrictable passageway being directly responsive to varying pressure of flowing spinning solution whereby the flow of said by-passed liquid pigment composition is controlled in accordance with the pressure of said spinning solution so that the flow of said liquid pigment composition being overfed to said point of injection is substantially equalized with that of said flowing spinning solution.

2. Method for directly incorporating a metering gear pump fed liquid pigment composition into a spinning solution under pressure for subsequent extrusion into amount of said liquid pigment composition into said 2,ss7,1.0a

spinning, solution at said point; and by-passing the overfed liquid pigment compositionthrough a constn'ctable passageway being directly responsive to varying pressure of flowing spinning solution whereby the flow of said by-passed liquid pigment composition is controlled in accordance with the pressure of said. spinning solution so that the flow of said liquid pigment composition being pumped to said point of injection is substantially equalized with that of said flowing spinning solution.

3. In the method according to claim 2 wherein said point of injection is overfed with said liquid pigment composition in an amount between about 3 and about 100 times the predetermined amount to be injected into said spinning solution.

4. In the method according to claim 2 wherein the pressure of the liquid pigment composition being pumped to the point of injection is substantially equalized within not more than about 2 pounds per square inch with the pressure of the flowing spinning solution.

5. Apparatus for incorporating a liquid pigment composition into a spinning solution flowing in a conduit under pressure for subsequent extrusion into colored yarn and like products comprising a supply reservoir for said pigment composition; a circulating pump with- 7 drawing from said supply reservoir connected in a series feeding arrangement to a metering gear pump for injecting said pigment composition into said spinning solution flowing in said conduit under pressure, said circulating pump having a larger delivery output than the capacity of said metering pump to ovcrfeed surplus quantities of said pigment composition to said metering pump; a return line from said circulating pump to said supply reservoir for circulating surplus quantities. of said pigment composition overfed to said metering pump by said circulating pump; a control valve in said return line responsive to varying pressure in spinning solution conduit; a constrictable passageway in said control Valve directly responsive to varying pressures of said spinning solution from said conduit and adapted to vary the rate of flow of said pigment composition circulating in proportion to the pressure of said spinning solution so that the pressure under which said pigment composition is fed to said metering pump is maintained 8 substantially equalized with that of said spinning solution in saidconduit.

6. Apparatus for incorporating a liquid pigment composition into a spinning solution flowing in a conduit, under pressure for subsequent extrusion into colored yarn and like products comprising a supply reservoir for said-pigment composition; a circulating pump withdrawing from said supply reservoir connected in a series feed arrangement to a metering gear pump for injectingsaid pigment" composition into said spinning solution flowing in said conduit under pressure, said circulating. pump having a larger delivery output than the capacity of said metering pump to overfeed surplus quantit-ies of said pigment composition. to said metering pump; a return line from said circulating pump .to said supply reservoir for circulating surplus quantities of said pigment composition overfed to. said metering pump by said circulating pump; a control valve in said return line responsive to varying'pressure in said spinning solution conduit; a constrictable passageway in said control valve provided by a flexible diaphragm in contact with said spinning. solution under pressure from said conduit; said constrictabl'e passageway being directly responsive to varying pressures of said spinning solution from said conduit in contact with said flexible diaphragm and adapted to vary the. rate of flow of said composition circulating in said return line in proportion to the pressure of said spinning solution so that the pressure under which. said pigment composition is fed to said metering pump ismaintained substantially equalized with that of said spinning solution in said conduit.

7. In an apparatus according to claim 6 wherein the delivery output of said circulating pump is between about 3 and about 100 times the capacity of said metering gear pump.

8. In an apparatus according to claim 6 wherein said flexible diaphragm is rubber.

References Cited in the file of this patent UNITED STATES PATENTS 

1. METHOD FOR DIRECTLY FOR INCORPORATING A METERING GEAR PUMP FED LIQUID PIGMENT COMPOSITION INTO A SPINNING SOLUTION UNDER PRESSURE FOR SUBSEQUENT EXTRUSION INTO COLORED YARN AND LIKE PRODUCTS COMPRISING, OVERFEEDING THE LIQUID PIGMENT COMPOSITION TO A POINT IN A CONDUIT PREDETERMINING THE AMOUNT TO BE INJECTED INTO A FLOWING SPINNING SOLUTION UNDER PRESSURE, INJECTING A PREDETERMINED AMOUNT OF SAID LIQUID PIGMENT COMPOSITION INTO SAID SPINNING SOLUTION AT SAID POINT, AND BY-PASSING THE OVERFED LIQUID PIGMENT COMPOSITION THROUGH A CONSTRICTABLE PASSAGEWAY BEING DIRECTLY RESPONSIVE TO VARYING PRESSURE OF FLOWING SPINNING SOLUTION WHEREBY THE FLOW OF SAID BY-PASSED LIQUID PIGMENT COMPOSITION 